The present invention relates to highway traffic lane and edge delineators and, more particularly, to an improved, inexpensive highway pavement marker which is useful over a wide range of roadway conditions
Today, it is common for highway traffic lanes and edges to be delineated by light reflective pavement markers. Such markers may be classified as either permanent or temporary. Permanent pavement markers generally comprise a hard plastic low profile base having inclined front and rear reflective faces. Permanent pavement markers are installed on lines defining traffic lanes and highway edges. Light is reflected from the reflective faces of the permanent pavement markers providing drivers with a clear visual indication of the traffic lanes and edges of the highway on which they are traveling. Although permanent pavement markers are relatively long lived, they are relatively expensive and require periodic maintenance In particular, with repeated striking by the tires of cars and trucks permanent pavement markers often become cracked or dislodged. When a permanent pavement marker becomes dislodged from a highway surface, it often leaves a cavity in the pavement which can result in a rapid erosion of the pavement surrounding the cavity. To prevent such occurrences requires regular monitoring of highway pavement markers and either the prompt replacement of dislodged pavement markers or pavement patching to fill the cavities left by dislodged markers.
Further, when permanent pavement markers are installed on highways in areas subject to snow conditions, they are regularly damaged and dislodged during normal snowplow operations. This has become such a serious problem in areas subject to heavy snows that either permanent pavement markers are not installed or specially designed protective ramps are installed adjacent the markers. However, such ramps are relatively expensive and have found limited commercial acceptance.
On many occasions, it is desired to delineate highway lanes and edges for relatively short periods of time such as several weeks or a few months. Under such conditions, it is common to utilize relatively inexpensive temporary pavement markers. Specific instances where temporary pavement markers have been utilized include road construction and repair situations where it is desired to temporarily delineate a modification in existing traffic lanes or where a highway is being resurfaced with the addition of an asphalt covering. In road resurfacing situations, temporary pavement markers are mounted along an existing traffic line. Then asphalt is poured over the roadway with the tops of the temporary pavement marker being exposed through the asphalt covering to provide and indication where a new traffic line should be painted.
Temporary pavement markers heretofore have been formed of a very inexpensive light weight plastic such as polyurethane which may be extruded to form single piece pavement markers having a T or L shape. The two most common of such temporary pavement markers are illustrated in FIGS. 1 and 2 of the drawing accompanying this specification.
As illustrated in FIG. 1, the T-shaped temporary pavement marker includes a flat base and a vertical leg extending from the base intermediate the forward and rear edges thereof. A layer of adhesive is fixed to the bottom of the base and covered with a protective paper until it is intended to install the temporary pavement marker. In this regard, installation of the temporary pavement marker illustrated in FIG. 1 simply requires the removal of the paper sheet, the placing of the base on a cleaned surface of the pavement and the application of foot or hand pressure to the top of the base to adhere the marker to the pavement. While it is intended that the marker of FIG. 1 have a useful life of several weeks, in actual practice, it has been found that it is very short lived. For example, after 5 or 6 cycles of tires striking a forward face of the vertical leg when the pavement temperature is about 100 degrees Fahrenheit or after 2 or 3 cycles when the pavement temperature is about 10 degrees Fahrenheit, the vertical leg assumes the inclined position as shown in dotted outline in FIG. 1 After about 20 cycles at a pavement temperature of about 100 degrees Fahrenheit or after about 5 cycles at 10 degrees Fahrenheit, the leg is permanently bent or fractured along its junction with the base to remain in a useless flat condition as illustrated by the broken outline in FIG. 1.
The L-shaped temporary pavement marker illustrated in FIG. 2 fairs no better under actual operating conditions. As illustrated, the L-shaped temporary pavement marker includes a flat base to which adhesive is secured and covered by a sheet of protective paper. A vertical leg is secured to and extends upwardly from the base at a rear edge thereof. At a pavement temperature of about 100 degrees Fahrenheit, 5 or 6 cycles of tires striking the leg will cause the leg to bend to an inclined position as illustrated by the dotted line in FIG. 2 Only 2 or 3 cycles are required when the pavement temperature is about 10 degrees Fahrenheit. After 15 cycles at a pavement temperature of about 100 degrees Fahrenheit or after 5 cycles at 10 degrees Fahrenheit the leg assumes a useless flattened condition or fractures along the junction with the base to remain in a flattened condition as illustrated by the broken outline in FIG. 2. Accordingly, unless such prior temporary pavement markers are installed on highways substantially free of vehicular traffic, their useful life is about less than 1 or 2 weeks. Certainly, such temporary pavement markers are nearly useless under snow conditions where plowing of highways is required.
Therefore, a need exists for a inexpensive pavement marker which will reliably delineate highway traffic lanes and edges over a wide range of pavement temperature conditions such as between -40 and 160 degrees Fahrenheit and which will resist damage and dislodging by vehicle tires and snow plows. The improved highway traffic lane and edge delineator of the present invention satisfies such needs.